1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material and, more particularly, to a silver halide color photographic light-sensitive material and a photographic light-sensitive material for color photography.
2. Description of the Related Art
Recently, requirements for higher performance, particularly higher sensitivities and higher image qualities of silver halide photographic light-sensitive materials have become more and more strict. To meet these requirements, efforts have been made to flatten an emulsion grain into a tabular grain to thereby increase the surface area of the grain. In addition, to improve the response to light of such a tabular grain, refinements have been made by performing spectral sensitization by using a relatively large amount of cyanine spectral sensitizing dyes as well as introducing dislocation lines into the grain and performing selenium sensitization.
In particular, a tabular grain with a high aspect ratio can increase the total surface area of a grain for the same volume and can therefore adsorb a large amount of compounds that determine the photographic sensitivity of an emulsion. In principle, therefore, such a tabular grain is advantageous in increasing sensitivity. In addition, to increase the number of grains contained in an emulsion layer at the same coating silver amount with the total surface area per grain maintained constant, a tabular grain having a high aspect ratio is advantageous in principle. Therefore, the tabular grain with a high aspect ratio possesses, in principle, very good properties in increasing sensitivity and image quality.
It was found, however, that one problem arises in attempting to maximally take advantage of these favorable properties of the tabular grain with a high aspect ratio; the graininess of the tabular grain with a high aspect ratio is degraded when the grain is forced to adsorb a large amount of compounds that determine the photographic sensitivity. This phenomenon is significant when an amount of compounds adsorbed is large or when a time interval in which an emulsion is left to stand in the form of a solution from addition of substances to be adsorbed is long. It is, therefore, crucial to reduce this degradation in graininess as a practical drawback of the tabular grain having a high aspect ratio, thereby sufficiently taking advantage of the preferable properties typical of a tabular grain.
JP-B-43-7541 ("JP-B" means Published Examined Japanese Patent Application) discloses the use of a synthetic polymer having an imidazole group as a protective colloid for use in grain formation instead of gelatin. JP-B-44-14152 discloses the use of a synthetic polymer having an imidazole group as a color turbidity inhibitor. However, these patents do not mention at all the ability of the present invention to prevent degradation in performance caused when a silver halide emulsion comprising tabular grains is aged in the form of a solution; that is, this effect of the present invention is totally unexpected.